Pusher-type furnace

ABSTRACT

A pusher-type furnace for the heating of metal ingots, blooms, billets or bars to rolling temperature, is provided at its inlet side with a billet-receiving platform or table upon which a pusher assembles one or more billets for advance into the furnace by a main pusher, the latter serving simultaneously to displace the entire array of workpieces and advance one or more of the latter out of the furnace.

United States Patent Sevenich et al.

PUSHER-TYPE FURNACE Inventors: Theodor Josef Sevenich, Dortmund;

Wolfgang Fabian, Dortmund-Hombruch; Klaus Kuhn, Dortmund, all

of Germany Assignee: Maschinenund Werkzeugbau GmbH, Dortmund-Hombruch,Germany Filed: Oct. 1, 1970 Appl. No.: 77,095

Foreign Application Priority Data Oct. 2, 1969 Germany ..P 19 49 747.3

US. Cl ..214/24, 198/221, 263/6 R Int. Cl ..F27b 9/22 Field of Search..2l4/23-25;

263/6 B; l98/22l [56] References Cited UNITED STATES PATENTS 3,490,6211/1970 Cook ..214/23 FOREIGN PATENTS OR APPLICATIONS 639,848 12/1936Germany l4/24 1,205,574 11/1965 Germany .Q .;214/23 PrimaryExaminer-Robert G. Sheridan Attorney--Karl F. Ross I ABSTRACT Apusher-type furnace for the heating of metal ingots, blooms, billets orbars to rolling temperature, is provided at its inlet side with abillet-receiving platform or table upon which a pusher assembles one ormore billets for advance into the furnace by a main pusher, the latterserving simultaneously to displace the entire array of workpieces andadvance one or more of the latter out of the furnace.

4 Claims, 1 1 Drawing Figures PATENTEU 24 I97? 3.700.122

w 64, 6 6c 68 60! v 6 7 I Theodor J Sevenich 7" Wolfgang Fabian E J 1Klaus KUhn 3 L. INVENTORS.

3 BY 65w 00 Attorney PUSHER-TYPE FURNACE FIELD OF THE INVENTION paratusand, more particularly, to improvements relating to pushertype furnacesand installations incorporating same. More particularly, the inventionrelates to an improved feed arrangement for a pusher-type furnace and toa method of operating same.

BACKGROUND OF THE INVENTION A pusher-type furnace generally comprises anelongated furnace chamber provided with means, e. g. a pair of rails forcarrying billets, bars, blocks, blooms, ingots and like workpiecesthrough a space which is heated by combustion or by regenerative-heatedgases, for heattreatment of the workpieces and especially, the heatingthereof to rolling temperature. In the furnace, hot gases contact theworkpiece both from above and from below and the relatively hotworkpiece discharged from the furnace may be directly subjected torolling or other metal deformation.

Furnaces of this type are disclosed in US. Pat. Nos. 3,245,672 and3,296,039. r

In general, a pusher-type furnace is provided at the charging or inletend of the furnace with a ram of like pusher member designed to advancea fresh workpiece into the furnace through a door or window thereof, tosimultaneously displace all of the workpieces within the furnace throughan increment equal to the width of the introduced workpiece, and toshift a workpiece at the discharge end of the furnace out of the outletdoor. The workpieces within the furnace lie in laterally contiguous(abutting) relationship and the furnaces operate more or lessperiodically with the period determined by the length of the furnace,the number of workpieces to be accommodated therein, the width 'of theworkpiece and the residence time of the workpiece within the furnacethat is considered desirable.

Such furnaces may be provided with supply means, e.g. a roller conveyorupon which the workpieces are delivered to the charging apparatus andwith discharge means, e.g. a roller conveyor, upon which the emergingworkpieces are carried to a further processing station, e.g. a rollingmill. The most convenient method of operating the furnace makes use of afurnace chamber or path having a width which is greater than the maximumlength of the billet or other workpiece to be treated and inserts theworkpieces laterally, the workpieces arriving in the longitudinaldirection upon the roller conveyor and being shifted transversely tothis direction into the furnace. The workpieces are then advancedperiodically or in increments through the furnace in a directiontransverse to their length.

Numerous installations established in recent years have made use of anumber of such pusher-type furnaces arranged in parallel relationbetween the supply conveyor and the discharge conveyor. One of theprimary problems encountered with such systems is the fact thatefficient use of the conveyor arrangements requires the periods of thepusher-type furnaces to be established with respect to one another suchthat the discharged workpieces do not encounter one another. This isaccomplished by operating all of the charging arrangementssimultaneously, thereby ensuring that a workpiece will be dischargedfrom each of the pushertype furnaces at each stroke. Hence each furnacemust be operated at the charging rate determined by the slowest furnace.More complex synchronization of the charging means have proved to beunsuccessful.

OBJECTS OF THE INVENTION It is, therefore, the principal object of thepresent invention to provide a pusher-type furnace installation whereinthe aforementioned disadvantages can be obviated.

Another object of the invention is the provision of an improved methodof operating a pusher-type furnace and especially a pusher-type furnaceadapted to be used in conjunction with similar pusher-type furnaces in aparallel array thereof.

Yet another object of the instant invention is to provide an improvedmethod of operating a pusher-type furnace installation which permitsaccommodation of individual furnace programs to workpieces of differentwidth without inconveniencing the operation of the entire system.

SUMMARY OF THE INVENTION The invention is based upon the discovery that,with existing installations of the character described, it is difficult,if not impossible to adjust the program of a particular furnaceconstituting part of an array of pusher-type furnaces adapted to besimultaneously operated to discharge onto a common conveyor arrangement.It will be readily understood that a change in the program is called forwhen any of the aforedescribed parameters is to be changed. For example,when narrow billets are to be heated, the periodic feed timing of thefurnace must be adjusted to advance the workpieces more rapidly throughthe furnace and vice versa. It follows that, with the existing systems,it was not possible to vary the width of the workpieces supplied at oneof the furnaces to the exclusion of the others. Hence the versatility ofthe entire system was limited.

It has now been found that this disadvantage can be overcome byproviding, at the charging end of a pusher-type furnace, a table orplatform for storage of the workpiece and, in addition to the mainpusher mechanism or ram means, an auxiliary pusher mechanism or rammeans of a stroke and periodicity which may differ from one furnace toanother while the strokes of the main rams and their operating rates maybe identical.

According to an essential feature of this invention, the auxiliary ramat the or each furnace operates at a rate which is equal to or greaterthan the rate of operation of the main pusher means.

According to an important feature of this invention, a pusher-typefurnace, which extends longitudinally between an inlet and an outlet andprovided with means for supporting a succession of workpieces betweenthe inlet and the outlet in contiguous relationship, if formed adjacentits inlet with a collecting table juxtaposed with or adjacent a feedconveyor adapted to carry a succession of workpieces to the furnace. Thefeed-pusher means (auxiliary ram) is longitudinally reciprocable todisplace a plurality of such workpieces generally transversely to thedirection in which they are delivered, onto the collecting table fortemporary storage thereon, during a stroke of the main pusher meanswhich delivers a previous workpiece, or group of workpieces, to thefurnace and thereby displaces all of the workpieces within the furnacethrough a corresponding distance in the direction of the outlet.

The conveyor means may be a gravity roller conveyor upon which theelongated workpieces are delivered in a direction parallel to theirmajor dimensions and transversely to the longitudinal direction of thefurnace.

The direction of reciprocation of the main pusher means andof the feedpusher means is, of course, transverse to the major dimensions of theworkpieces but parallel to the longitudinal direction of the furnace,i.e.

in the direction of the inlet and in the direction of movement of theworkpieces through the furnace from the inlet to the outlet.

According to the principles of the invention, the main pusher means isoperated at a constant rate regardless of the program of the furnacewhile the feed pusher means'is operated at a rate determined by the Iwidth of the workpieces to be heat-treated. Hence, the feed pusher meansmay deliver single workpieces to the collecting table for each stroke ofthe main pusher means when such workpieces have the maximum width whichmay be accommodated, or may be operated at a frequency or rate whichexceeds that of the main pusher means to accommodate a plurality ofworkpieces upon the collecting table for each stroke of the main pushermeans. This latter mode of operation is used when the width of theworkpieces is less than the maximum width as will be apparenthereinafter.

The term main pusher means" is used herein to designate the pusherarrangement commonly provided at such furnaces in prior art systems andgenerally includes a drive speed-reducing gearing and one or more pusherbars reciprocated by such gearing. The drive may be independent from orcoupled with the drives of similar furnace installations.

Theauxiliary ram or feed-pusher means, additionally provided inaccordance with the principles of the the main pusheris reduced inaccordance with the principles of this invention, additional place isavailable for storage of billets, etc.

Still another feature of this invention resides in the provision ofswinging flaps, pawls or dogs upon the pusher bars, to enable them toclear the workpieces when the pusher bars are drawn away from thefurnace inlet and to engage the workpieces along their trailing edgeswhen the workpieces are to be advanced in the direction of the furnaceinlet.

DESCRIPTION OF THE DRAWING The above and other objects, features andadvantages of the present invention will become more readily apparentfrom the following description, reference being made to the accompanyingdrawing in which:

FIG. 1 is a vertical cross section through a pushertype furnaceinstallation embodying the present inventlOn ;j'-

. FIG. 2 is a plan view thereof; g

FIG. 3 is a detail view of a pusher-ram'for use in the installation ofFIGS. 1 and 2; "and FIG. 4A'-- 4H are diagrammatic side elevationalviews illustrative of various phases of the invention.

SPECIFIC DESCRIPTION Referring first to FIGS. land 2 of the drawing, itwill be apparent that the furnace installation, which may comprise aplurality of parallel pusher-type furnaces only one of which has beenillustrated, basically includes the pusher-type furnace 1 having apreheating chamber 1a, a main heating chamber 1b and atemperature-equalizing chamber 10 horizontally spaced along a lineartransport path 1d for a succession of bars, billets, blooms or otherprismatic workpieces of iron, steel or other metal .to be rolled. Theworkpieces are generally shown at'3 and have a length L and a width w orW as illustrated in FIG. 2. Some of the billets may, of course, be widerthan others as represented in FIG. 1. The support 1d maybe concentratedby a pair of rails extendpresent invention, preferably includes an,independently operable second drive means, e.g. a motor,speed-reducing. gearing and control means, for reciprocating the pusherbars of the feed-pusher means. The second drive means may be included inthe same structure as the drive means for the main pusher bars or in aseparately provided auxiliary structure. Since only individualworkpieces need be displaced by the feed-pusher means, the drive for thelatter and the pusher bars themselves may be diminished to withstandsubstantially less stress than is applied to the main pusher means.Furthermore, since the main-pusher means does not have to shift theworkpieces onto the table, the stroke thereof can be reduced and themain pusher operated at a slow speed convenient to the optimalefficiency of the drive means.

The system has been found to be particularly advantageous when thefurnace installation is used as part of a broad-band or strip rollingmill for heating the billets prior to rolling. The improved feedarrangement for the furnace installation may have its. program adjustedin accordance with the widths of the workpieces to be processed withoutnegative influence upon the remainder of the processing line. Since thestroke of ing across heating chambers in the manner described andillustratedin the aforementioned US. patents.

. At the charging side of the furnace, there is provided an inlet door1e beyond which an accumulating storage or collecting platform or table5 extends horizontally in alignment with the upper surface of theworkpiece supports within the furnace. The table 5 has a width D inexcess of the maximum width W of a workpiece to be accommodated by thefurnace and equal at least to the maximum stroke of the main pusher-ram7 as will be apparent hereinafter. The exhaust-gas outlet is representedat 1 f and a furnace chamber is shown at 1g.

Each of the pusher-type furnaces 1 is disposed between .a pair ofconveyors generally indicated at 4 and 12 and respectively constitutingthe inlet and discharge conveyors, respectively. The roller conveyorsare inclined downwardly in the direction of advance of the workpieces asdescribed at pages 10 74 ff. of MARKs MECHANICAL ENGINEERS Handbook,McGraw Hill Book Co., New York 1958. The conveyors 4 and 12 run alongthe entire bank of pusher-type furnaces in the usual manner and define asupport plane P which is identical with that of the upper surface of thetable 5. At the discharge side of the furnace, an outlet opening 1h isprovided, together with a support table lj, the upper surface of whichis coplanar with the uppermost portions of the rollers 12 of thedischarge conveyor.

From FIGS. 1 and 2, it will be apparent that-each of the workpieces 3travels along the charging conveyor 4 across the open mouth of thepusher-type furnace in the direction parallel to its length, in thedirection represented by arrow A and is advanced into the furnace 1 inthe direction of arrow B, thereby bringing its longitudinal edge 3' intocontact with the rearward edge 3" of the previous workpiece. Continuedmovement of the workpiece 3 to the right (FIG. 2) pushes the entirecollection of laterally contiguous workpieces to the right and therebyadvances the workpiece at the distal end of the furnace out through thedoor 1h onto the table lj and finally onto the conveyor 12 where it runsby gravity in the direction of arrow C to a rolling mill or the like-The feed means for the workpieces is constituted, ac

cording to the present invention, by a main ram having a'pair of pusherbars 6 which may be reciprocated in the longitudinal direction of thefurnace l, i.e. in the direction of arrow D, but which lie in ahorizontal plane above the plane P of the table 5. At the free ends ofthe pusher bar 6, proximal to the furnace, there are provided swingableshoes 7 adapted to engage the trailing edges of the workpieces andadvance them into the furnace. A suitable arrangement of this shoe isshown in FIG. 3 which also discloses that the bars 6 may be constitutedas racks 6a engageable by pinions 6b coupled with an adjustable drive 11which may be provided with a heavy-duty motor by speed-reducing gearwith the pusher bar to deliver the relatively high torque necessary toadvance all of the workpieces within the furnace. The drive 11 is, ofcourse, shown only diagrammatically and may be constituted by the commondrive for the main pusher members of all the furnaces of the respectivebank. 7

Referring further to FIG. 3, it will be seen that the free ends of thebars 6 are bifurcated with the pawl-like flap 7 articulated in a slot 6cbetween the arms 6d of the bifurcation upon a pin 6e. When the bar 6 isretracted (arrow E) and the pawl 7 engages the forward or leading edgeof a laterally shiftable workpiece as represented at 3' in FIG. 3, thepawl 7 swings in the counterclockwise sense to clear the workpiece andreturns into its dot-dash line position in the clockwise sense onlyafter the workpiece has been cleared. Furthermore, the trailing edge 7of the pawl is designed to abut floor 6f of the bifurcation during thefollowing forward displacement of the bar 6 when the leading edge 7" ofthe pawl engages the trailing edge 3 of the workpiece 3. Upon suchabutment, the pawl cannot swing in the clockwise sense and hence theworkpiece is entrained along with the pawl. A similar self-clearing pawlis provided at the free end of each of the spaced-apart rams 6. A secondbar of rams 9 is provided between the rams 6 and constitute theauxiliary pusher means of the present invention, designed to advance theworkpieces from the conveyor 4 onto the table 5 as will be apparenthereinafter. The stroke of the main pusher means may, of course, bereduced of the stroke of auxiliary pusher means. The auxiliary pushermeans 9 comprises a pair of pusher bars or rams, spaced transverselyacross the mouth of the furnace and substantially coplanar with the rams6 although a vertical offset has been represented in FIGS. 4A 4H forclarity of illustration. At the free ends, the bars 9 are provided withswingable pawls 10 as previously discussed. The drive means for the bar9, may include a rack and pinion arrangement of the type represented inFIG. 3, and makes use of a motor 8 and appropriate speed-reducinggearing. The speed-reducing gearing, rack and pinion arrangements andcontrol means are provided within the housing shown at 2, the latterreference numeral being used hereinafter to designate the workpiece-feedmeans generally.

The operation of the system will be understood more readily from FIGS.4A 4H in which a typical sequence is shown. A workpiece arriving uponthe gravity roller conveyor 4 generally will have a maximum width Wandis shiftable to the right onto the table 5 by the rams 9 and isthereafter advanced into the furnace by the rams 6 until, of course, thefurnace is full. During movement through the furnace, the workpieces areheated to rolling temperature so that, when a further workpiece ispushed into the furnace, a workpiece of corresponding width is pushedout of the furnace onto the conveyor 12 and passes by gravity inthe'direction of arrow C to the rolling mill. When, however, it isdesired to reduce the width of theworkpiece to the width w, whichpreferably constitutes a simple fraction of the width W, i.e. w (l/n) XW, where n is an integer, n workpieces are accumulated upon the table 5and are advancedsimultaneously into the furnace by the rams 6. In thiscase, the rams 9 may operate at a frequency f n X F, where F isfrequency of operation of the main pusher rams 6.

For the heating of billets or other workpieces of a width Wcorresponding to the maximum width of the workpieces to be processed,the auxiliary pusher means 9, 10 shifts to the right (FIGS. 1 and 2) todisplace the workpiece from the gravity roller conveyor 4 along whichthe workpiece travels in the longitudinal direction A. The workpiece isthereby moved transversely onto the table 5 whereupon the main pushermeans 6, 7 engages the trailing edge of the workpiece and moves it tothe right into the furnace by a distance approximately equal to W. Allof the workpieces within the furnace are thereby shifted to the rightand the workpiece 3a at the discharge end is thereupon pushed out of thefurnace onto the table lj and, subsequently, onto the roller conveyor 12which carries it in the longitudinal direction C to the rolling mill.

When it is desired to change the rolling program and, for example, makeuse of billets or workpieces of a smaller width w, e.g. a workpiecehaving a width w k W (n 2) the drive 8 is operated to effect two strokesof the feed pusher 9 as best seen in FIGS. 4A 4H. Assume, in FIG. 4Athat the main pusher 6 is advancing the workpiece 3 in the direction ofarrow B into the furnace from the table 5 as previously described.Simultaneously, the pusher 9 is operated with a smaller stroke in thesame direction to advance a workpiece 3c of smaller width in thedirection of arrow B onto the table. When two such workpieces 3c and 30'have been deposited upon the table, the pusher 6 moves rearwardly (arrowB so that its pawl 7 rides over the workpieces 3c and 30' to engage therearrnost of these a 7 workpieces (FIGS. 4B and 4C) collected upon thetable 5 as the pusher 9 begins its rearward movement (arrow B Withpusher 9 continuingits rearward movement, the pawl 7 locks in place(FIG. 4D) against its abutment and the pusher 6 begins itspower stroke(arrow B to carry the two workpieces into the furnace with atotalstrokefof approximately W. Meanwhile pusher 9 accumulatesadditional workpieces upon the table as'shown in FIGS. 4E 4H and thecycle is repeated. The latter Figures also demonstrate thatsubstantially any number of workpieces can be collected on the tabledepending, of course, upon the total stroke S of the main pusher. With astroke S, which may be approximately equal to W, the largest workpiecewidth accommodated by the apparatus, the stroke of the main pusher mayremain unaltered while workpieces are discharged from the furnace outletin a cumulative width Wor S.

The improvement described and illustrated is believed to admit-of manymodifications within the ability of persons skilled in the art, all suchmodifications being considered within'the spiritand scope of theinvention except as limited by the appended claims.

We claim:

1 A pusher-type furnace installation comprising:

a pusher-type furnace having an inlet at one end and I an outlet atanother end thereof and provided with V means for supporting asuccession of workpieces in contiguous relationship within said furnace;a collecting table ahead of said inlet; feed-pusher means for advancinga plurality of workpieces,

onto said table in the longitudinal direction of said furnace; and

8 I main pusher means for simultaneously advancing the workpieces ontosaid table into said furnace while shifting the workpieces therein acorresponding distance said outlet,

said main pusher means comprising: a main pusher bar reciprocable insaiddirection,

first drive means operably'connected with said main pusher'bar, w e v apivotal pawl on said main pusher bar adapted to I ride over workpiecesonsaid table and to lock upon advance of said ma-pusher bar in thedirection of said inlet; said feed-pusher means including: 7 afeed-pusher bar reciprocable insaid direction, .second drive meansoperableindependently of said first drive means and connected to saidfeed-pusher bar for reciprocating same during reciprocation of said mainpusher bar, and a pivotal pawl on said feed-pusher bar adapted to rideover workpieces upon displacement of said feed-pusher bar away'from saidinlet and to engage the workpieces upon advance of the feed-pusher barin the direction of said inlet. '7 v 2. The installation defined inclaim 1 wherein said 4. The installation defined in claim 1 wherein agravity roller conveyor is provided adjacent said table for r deliveringsaid workpiec es t o sa id feed-pusher means.

1. A pusher-type furnace installation comprising: a pusher-type furnacehaving an inlet at one end and an outlet at another end thereof andprovided with means for supporting a succession of workpieces incontiguous relationship within said furnace; a collecting table ahead ofsaid inlet; feed-pusher means for advancing a plurality of workpiecesonto said table in the longitudinal direction of said furnace; and mainpusher means for simultaneously advancing the workpieces onto said tableinto said furnace while shifting the workpieces therein a correspondingdistance said outlet, said main pusher means comprising: a main pusherbar reciprocable in said direction, first drive means operably connectedwith said main pusher bar, a pivotal pawl on said main pusher baradapted to ride over workpieces on said table and to lock upon advanceof said mapusher bar in the direction of said inlet; said feed-pushermeans including: a feed-pusher bar reciprocable in said direction,second drive means operable independently of said first drive means andconnected to said feed-pusher bar for reciprocating same duringreciprocation of said main pusher bar, and a pivotal pawl on saidfeed-pusher bar adapted to ride over workpieces upon displacement ofsaid feed-pusher bar away from said inlet and to engage the workpiecesupon advance of the feed-pusher bar in the direction of said inlet. 2.The installation defined in claim 1 wherein said first and second drivemeans and said main pusher bar and feed-pusher bar are mounted in acommon structure.
 3. The installation defined in claim 1 wherein saidfeed-pusher bar is reciprocated at a higher speed than said main puSherbar.
 4. The installation defined in claim 1 wherein a gravity rollerconveyor is provided adjacent said table for delivering said workpiecesto said feed-pusher means.